1. Field of the Invention
The present invention relates to a linear guide device for an automobile vehicle steering column.
The device according to the invention applies in particular to a steering column whose depth and/or inclination can be adjusted and whose steering shaft is mounted inside a body-tube which is supported on and immobilized to the body of the vehicle in the required position. The steering column includes a steering shaft rotatably mounted inside a body-tube which is connected to a support assembly fixed to the chassis of the vehicle or to an element of the body of the vehicle. The invention can also be applied to a non-adjustable steering column, in which case the body-tube is mounted directly in the support assembly.
2. Description of the Prior Art
The ongoing improvement to the safety of steering columns requires manufacturers to master all parameters of energy absorbing systems. Accordingly, with particular reference to the method of absorbing energy by unwinding a wire, which is increasingly used on steering columns, it is necessary to prevent the mobile assembly moving relative to the fixed assembly at the time of impact with unintentional resisting forces which are due to wedging, clamping or play phenomena. All these drawbacks are associated with poor linear guiding of the mobile assembly relative to the fixed assembly.
The object of the present invention is to propose a linear guide device for guiding the mobile assembly of an automobile vehicle steering column relative to the fixed assembly at the time of impact to prevent the occurrence of unwanted forces that interfere with the required absorption of energy.
Moreover, the linear guide device must be easy to mount within the overall dimensions of existing steering columns.
The invention relates to a linear guide device for an automobile vehicle steering column, which device includes a steering shaft rotatably mounted inside a guide-tube which is connected to a support assembly which is fixed to a chassis of the vehicle. The linear guide device includes a fixed support member which is adapted to be fastened to said chassis of said vehicle and a mobile support member which is adapted to be connected to said fixed support member in order to constitute said support assembly and which is immobilized to said fixed support member against forces up to particular value such that it is no longer immobilized in the event of an impact, said device further including rolling members which are disposed between a fixed rollway formed on said fixed support member and a mobile rollway formed on said mobile support member, said fixed rollway and said mobile rollway each lying in the required guidance direction.
In a embodiment of the invention, the linear guide device is adapted to operate in a guidance direction that is raised toward the front relative to a horizontal plane so that in the event of an impact the steering wheel is raised and pushed forward.
In another embodiment of the invention, the linear guide device is adapted to operate in a guidance direction that is inclined toward the front relative to a horizontal plane so that in the event of an impact said steering wheel is lowered and pushed forward.
Advantageously, the rolling members are balls. Moreover the roller members have a retaining cage to guarantee the position of said rolling members relative to each other.
According to some structures of the invention, at least one fixed rollway is formed on a fixed slide which constitutes an independent member mounted on and fixed to said fixed support member; and at least a mobile rollway is formed on a mobile slide which constitutes an independent member mounted on and fixed to said mobile support member.
According to other structures of the invention, at least one fixed rollway is formed directly on said fixed support member and constitutes an integral part of said fixed support member; and at least a mobile rollway is formed directly on said mobile support member and constitutes an integral part of said mobile support member.
According to an interesting feature of the invention:
said fixed support member has a fixed slide disposed in a housing on each of its uprights;
a corresponding fixed rollway is formed in each fixed slide;
said mobile support member has a mobile slide on each of its lateral portions, one end of which has a tenon which engages in a notch formed in the corresponding lateral portion, said tenon being extended by a tongue substantially parallel to said mobile slide so as to come into contact with an inner face of the corresponding lateral portion, the other end of said mobile side having a hole through it facing another hole through the corresponding lateral portion to receive means for fixing said mobile slide to the corresponding lateral portion;
a corresponding mobile rollway is formed in each mobile slide; and the balls are disposed between said fixed rollway and said mobile rollway.
Advantageously, according to the invention, the fixed rollways have axes inclined at an angle to the axis which represents the guide direction.
In another structure, the mobile rollways have axes inclined at an angle to the axis which represents the guide direction.
In another embodiment, the fixed rollways have axes inclined to the axis which represents the guide direction and said mobile rollways have axes inclined to the axis which represents the guide direction.
The linear guide device according to the invention therefore has the advantage of having a structure that is extremely simple to produce, allowing the possibility of very high manufacturing quality when mass-produced, as is the case in the automobile industry. This simplicity of manufacture also leads to a very low cost. The linear guide device according to the invention finally has the decisive advantage of preventing the occurrence of unwanted forces that interfere with the required absorption of energy. Thus the linear guide device absorbs energy in the required manner. Moreover, the device is easy to fit within the overall dimensions of existing steering columns.